Segmented Downhole Tool

ABSTRACT

A downhole tool includes a plurality of segments positioned on a core member. This construction is particularly suitable for sleeves, stabilizers and drill bit gage pads used in the formation of oil and gas wells. Worn or damaged segments can be replaced without the need for replacing the entire unit. The segments may include spiral vanes for directed fluid upwardly to the well head.

BACKGROUND OF INVENTION

1. Field of the Invention

This invention is related to downhole tools used in drilling oil or gas wells. Such tools include, for example, sleeves, stabilizers and drill bits.

2. Description of Related Art

Currently downhole tools such as sleeves, stabilizers and drill bits used for various purposes during the course of drilling an oil or gas well are formed as a single piece unit. Such an array of tools is shown in WO2009/073656 A1. The sleeves, stabilizers and drill bits typically include a plurality of spiral vanes with fluid passageways between them to allow for upward flow of drilling fluid. The pitch of the vanes is selected according to the conditions at the bottom of the well and the composition of the well bore at any given vertical or horizontal position. Various portions of the tool are subject to uneven wear which requires replacing the entire unit. Also, the pitch of the vanes once manufactured is fixed in a given unit and can not be altered to create customized fluid flow in different applications associated with a downhole tool used in forming and/or completing wells.

BRIEF SUMMARY OF THE INVENTION

The invention of this application is forming downhole tools in segmented discrete portions. This allows for replacing worn portions of the tool with a new segment rather than replacing the entire unit. This saves time and materials. This also allows for the ability to adjust the flow path of the fluid around the tool by providing segments having vanes with different pitch angles and blade thicknesses. Thus the operator of the drilling rig can vary the flow characteristics depending on varying conditions within the well.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING(S)

FIG. 1 is an elevation view of a tool according to an embodiment of the invention.

FIG. 2 is a perspective view of the tool showing two of the segments separated.

FIG. 3 is a longitudinal cross sectional view of the tool.

The drawings are intended to illustrate the various aspects of the invention and are not intending to be limiting, nor are they necessarily drawn to scale.

DETAILED DESCRIPTION OF THE INVENTION

As shown in FIGS. 1 and 2, the sleeve or stabilizer 10 according to an embodiment of the invention includes a hollow core member 21 having an upper threaded portion 12 which is known in the art as an API connector. Threads are provided at 14 for connection to an interiorly threaded portion of a tubular member which may be the drill tube. Breaker slots 16 are also provided for gripping by an appropriate bit breaker. Also shown in FIG. 1 is a plurality of stabilizer or sleeve segments 20. Although four are shown it is understood that any number of segments may be provided in accordance with the invention. Each segment includes plurality of vanes 22, 24, 26 and 28 respectively. The segments are mounted on the core member which extends from top portion 12 to bottom portion 30. The lower portion of the core member may be internally threaded as shown in FIG. 3 to receive a connection portion of another tool such as a drill bit. Lower collar member 32 may be provided with internal threads that engage threads on the lower exterior portion of core member 21. In lieu of threads, lower collar member 32 may be welded to core member 21. Upper and lower collar members 18 and 32 serve as transition members between the core and the segments 20. They may be provided with vanes 19 and 30 that line up with the vanes 22 and 28 of the adjacent segments.

FIG. 2 illustrates a way to attach the segments to core 21 and to each other. For preventing rotation of the segments with respect to each other, recesses 40 may be provided the top surface of the vanes as shown in FIG. 2. Pins 43 shown in FIG. 3 are adapted to fit within recesses 40 in the lower surface of an adjacent vane. To prevent rotation of the segments about core member 21, holes 42 are formed in the passageways between the vanes and extend to the inner surface of the segments. A suitable set screw, welded pin, press weld pin, threaded pin or any other known securing means can be inserted into the hole for securing the segment to the core member 21. It is understood that there are many other techniques and mechanisms that could be used to attach the various components to each other, all of which could be used in the context of this invention. Upper collar member 18 may be welded to core member 21 or secured to it by any well-known arrangement.

FIG. 3 illustrates an arrangement of the segments and collars on the core. The core includes an upper connection portion 12 known as an API connector and a lower integral portion 21 formed as a hollow cylindrical body. Upper collar member 18 and segments 20 have an internal diameter slightly greater than the external diameter of cylindrical portion 21 of the core so that they can slide over the outer surface of core portion 21.

The exterior lower surface of core portion 21 has inwardly extending threads 46 that are adapted to fit corresponding threads 47 provided on the interior surface of lower collar 32. The lower interior portion of core member 21 has threads 45 that are adapted to receive a standard API connector. In lieu of a threaded connection, lower collar member 32 may simply be welded to core member 21.

To assemble the sleeve or stabilizer, top collar 18 is positioned onto core member 21. Segment members 20 are then fitted on core 21 with the pins 45 aligning with the holes 40 in adjacent segments. A set screw or pin is then inserted through holes 42 to secure the segments to the core member 21. Finally lower collar is threaded or welded to the lower portion of the core thereby capturing the segments on the core member between the upper and lower collar members.

If during use one of the segments experiences more wear than the other, the drill string can be withdrawn from the well and only the worn segment need be replaced.

Also, it is contemplated that a plurality of segments with different pitch angles could be provided at the well site to allow the drill operator the flexibility to choose among several options depending on the drilling conditions. Each segment could also have a different pitch angle and blade thickness.

Although the present invention has been described with respect to specific details, it is not intended that such details should be regarded as limitations on the scope of the invention, except to the extent that they are included in the accompanying claims. 

1. A downhole tool comprising: a core member; and a plurality of separable segments fitted over and secured to the core member.
 2. A down hole tool according to claim 1 wherein the tool is a stabilizer, and the segments include a plurality of vanes.
 3. A downhole tool according to claim 1 including an upper and a lower collar on the core member, and the segments are located on the core member between the upper and lower collars.
 4. A downhole tool according to claim 1 wherein the core member is a hollow tubular member.
 5. A downhole tool according to claim 1 wherein the core member has an upper threaded portion for connection to a tubular element and has a lower threaded portion for connection to a drill bit or other tool.
 6. A downhole tool according to claim 1 wherein adjacent segments have cooperating pins and holes to prevent rotation between the segments.
 7. A downhole tool according to claim 1 wherein each segment has a hole from its exterior surface to its interior surface and a pin positioned within the hole forced up against the core member to prevent rotation of the segment with respect to the core member.
 8. A downhole toll according to claim 1 including an upper and a lower collar welded to the core member, and the segments are located on the core member between the upper and lower collars.
 9. A method of repairing a worn downhole tool used during the formation of an oil or gas well comprising: providing a downhole tool as claimed in claim 1; withdrawing the tool from the well; and replacing the worn out segment of the tool with a new segment or modifying blade configuration by changing pitch or blade widths. 